A height adjustment device of the generic type is described, for example, in WO 2006/012858 A1. Laterally from the telescoping shock absorber of a McPherson strut unit wheel suspension there is an electric motor which by way of a toothed-gear drive turns the bearing spring disk which is made as a ring nut. The ring nut is located on a threaded section of the shock absorber tube. Turning the ring nut by means of the electric motor can adjust the height of the body of the motor vehicle, for example, from a high level position by way of a normal level position into a low level position. The bearing spring here is turned with the ring nut as the level is being set, the spring constant as such remains essentially unchanged. If in such a wheel suspension there is an overload spring which limits the deflection path, for example, a rubber-elastic stop buffer, the spring path of the wheel suspension is changed by the overload spring which moves into the active position sooner or later with respect to the normal level position.
In another known height adjustment device, the base of the bearing spring, i.e., the body-side spring disk, is likewise changed in height and thus the height of the vehicle over the roadway is changed. The actuator necessary for this purpose is located partially within the longitudinal member of the body which has been changed for this purpose. The required actuator is an electrically driven ball screw. The assigned ball screw spindle is caused to rotate by way of a gear stage by an electric motor which is located within the spindle. The nut which is connected to the adjustable spring disk accordingly executes a lifting motion. In this way, the bearing spring moves the wheel carrier into the vertical position which is dictated by the control. The bearing spring itself remains unchanged in its length in the respectively examined loading state. After the adjustment process, a trip-free mechanism prevents the vehicle from sinking by its own weight in the de-energized state due to the ball screw which is not self-locking. The deflection path of the wheel is determined by the body-side overload spring which is located in the upper shock absorber receiver. In contrast, the rebound path of the wheel is determined by a tension stop which is located in the shock absorber itself.
DE 10 2004 018 701 B3 furthermore discloses variably limiting the deflection path of the wheel suspension for motor vehicles by the overload spring being supported on the telescoping shock absorber by way of an electrical actuating motor in two positions which are axially offset to one another on the body of the motor vehicle. This is intended to prevent the wheel rubbing against the inside of the wheel housing of the body of the vehicle and causing damage at larger wheel circumferences, for example, by mounting snow chains.
The object of the invention is to propose a device for adjusting the height of the body of a motor vehicle which, with structurally simple means, enables greater mechanical degrees of freedom in the design of the bearing spring and overload spring with consideration of favorable spring paths of the wheel suspension.